A titrator piston

Abstract

The utility model discloses a titrator piston. The utility model discloses, include: piston rod, the piston rod is by mounting spare and connecting spare, the outer surface of connecting spare is provided with screw thread, the bottom of piston rod outer surface is provided with tetrafluoro piston. The utility model discloses, because tetrafluoro piston is composed of polytetrafluoroethylene, and the outer surface of tetrafluoro piston is provided with multilayer sealing structure, and is provided with cavity on tetrafluoro piston simultaneously, and the three cooperation solves the lubricant of piston's dependence nodus and elastomer aging failure's problem, makes the detection result repeatability of titrator rise simultaneously, from 0.09% rise to 0.04%, and the bottom of tetrafluoro piston is coniform and cooperates with the cavity on tetrafluoro piston, makes the solution in burette enter the inside of cavity when being extruded, thereby avoiding that bubble can be attached on the surface of tetrafluoro piston, thereby solves the bubble stagnation effect problem of piston.

Description

Technical Field

[0001] This utility model relates to the technical field of pistons for titrators, specifically a titrator piston. Background Technology

[0002] As a core analytical instrument in modern laboratories, the measurement accuracy and reliability of a potentiometric titrator directly depend on the performance of its piston drive system. During titration, the piston mechanism plays a crucial role in precisely controlling the titrant flow rate; its mechanical stability, sealing performance, and motion accuracy directly impact the accuracy of the titration results. With the development of analytical chemistry towards micro and trace detection, traditional piston structures are gradually revealing technical limitations in terms of long-term stability, corrosion resistance, and contamination prevention. The pistons currently used in titrators have the following defects:

[0003] Accumulated transmission chain errors: The piston in existing titrators moves via a gear-screw system. Due to the dual errors of "backlash" (approximately 0.05°) and "elastic deformation" in the gear-screw system, the stepper motor on the titrator needs to move an additional 0.2mm to 0.3mm to compensate for the mechanical backlash during reversal, resulting in volume deviation exceeding the tolerance in the initial titration stage (measured positive deviation reaches 0.5%). This error proportion increases significantly, especially in micro-titrations (less than 100μL). Schmidt's (2021) "friction-inertia dual-state model" indicates that when the piston's starting acceleration is less than 0.2m / s², the error proportion increases significantly. 2 When static / dynamic friction changes abruptly, a stick-slip phenomenon occurs, which can cause low-flow titration pulsation in the titrator.

[0004] Dynamic connection failure: Although the anti-dislodgement structure of the glass stopcock is limited by a sleeve, fretting wear exists between the locking rod (φ2mm) of the hinged semi-ring and the locking hole. Accelerated life testing shows that after 3000 rotations, the spring return stroke decreases by 40%, posing a risk of accidental unlocking. The metal locking rod is prone to pitting corrosion in a halide ion environment; a 72-hour NaCl (0.5%) test showed pits larger than 10μm.

[0005] The problem of lubricant dependence: The gap (5-10μm) between the frosted surfaces of the glass stopcock must be filled with lubricant. Vaseline dissolves in organic solvents such as acetone and chloroform, contaminating the titrant and interfering with endpoint determination in photometric methods. At high temperatures (above 40℃), the viscosity of the lubricant decreases, leading to liquid film rupture and creeping leakage during titration.

[0006] Elastomer aging failure: Although the silicone ring of the Teflon composite piston is protected by an outer layer, stress relaxation occurs under continuous compressive stress (0.8 MPa). Accelerated aging tests at 70°C (500 h) show that the sealing contact pressure drops to 0.3 MPa, and the leakage rate increases from 0 μL / min to 2.5 μL / min. Users need to replace the piston every 6 months, increasing operating costs.

[0007] Geometric defects at the piston tip induce a bubble retention effect: Traditional planar or grooved structures generate Cassie states, allowing bubbles to adhere stably at the solid-liquid interface. Especially with low surface tension reagents (γ < 30 mN / m, such as ethanol solutions), the residual bubble volume at the concave corner can reach 1.2% of the total titration volume (25 mL burette). Although improved to a spherical convex surface (R = 1.5 mm), bubbles still nucleate at the apex when the contact angle is greater than 90°. Molecular dynamics simulations by Wong et al. (2022) confirm that surface nanoscale grooves (less than 50 nm) generate local negative pressure, stabilizing the bubble nucleus. Utility Model Content

[0008] The purpose of this invention is to provide a titrator piston to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, this utility model provides the following technical solution: a titrator piston, comprising:

[0010] A piston rod, comprising a mounting component and a connecting component, wherein the outer surface of the connecting component is provided with threads, and a PTFE piston is provided at the bottom of the outer surface of the piston rod;

[0011] The PTFE piston has a connection port at the middle of its top and a cavity on the outer ring at its bottom.

[0012] By adopting the above technical solution, the piston rod and the PTFE piston are connected by threads, thus solving the problem of dynamic connection failure and preventing the piston from falling off during use. In addition, the PTFE piston is provided with a cavity, which allows the PTFE piston to be used with different burettes of the same model. Due to the presence of the cavity, air bubbles are less likely to adhere to the surface of the PTFE piston.

[0013] Preferably, the outer surface of the mounting component is provided with mounting holes.

[0014] By adopting the above technical solution, the mounting component is connected to the limiting mechanism through the mounting hole, which avoids the piston from moving out of the range and prevents the burette from being damaged.

[0015] Preferably, the PTFE piston is composed of polytetrafluoroethylene (PTFE).

[0016] By adopting the above technical solutions, polytetrafluoroethylene has excellent heat resistance, chemical resistance and electrical insulation properties, solving the problems of lubricant dependence and elastomer aging failure.

[0017] Preferably, the connection port consists of a slot and a threaded hole, and a retaining ring is provided at the bottom of the outer surface of the mounting component. The mounting component is engaged with the PTFE piston through the retaining ring and the slot, and the connecting component is threadedly connected to the PTFE piston through the thread and the threaded hole.

[0018] By adopting the above technical solution, the mounting component can be stably installed on the PTFE piston through the fit between the retaining ring and the retaining groove, while the connecting component can be stably installed on the PTFE piston through the fit between the thread and the threaded hole. The combination of the two improves the stability of the connection between the piston rod and the PTFE piston and solves the problem of dynamic connection failure.

[0019] Preferably, the outer surface of the PTFE piston is provided with a multi-layer sealing structure.

[0020] By adopting the above technical solution, the sealing structure is composed of a sealing ring, which alleviates the problem of lubricant dependence.

[0021] Preferably, the bottom of the PTFE piston is conical.

[0022] By adopting the above technical solution, since the bottom of the PTFE piston is conical, the solution in the burette is guided into the cavity by compression, making it difficult for air bubbles to adhere to the surface of the PTFE piston.

[0023] Compared with the prior art, the beneficial effects of this utility model are:

[0024] 1. The piston of this titrator, due to the tight connection between the piston rod and the PTFE piston through threaded connection and clamping, eliminates the gap between the piston rod and the PTFE piston, improving the stability of the detection structure. The precision of the analysis and testing structure increases from 0.08% to 0.03%, thereby solving the problems of transmission chain error accumulation and dynamic connection failure.

[0025] 2. The piston of this titrator, because the PTFE piston is made of polytetrafluoroethylene and the outer surface of the PTFE piston is provided with a multi-layer sealing structure, and a cavity is provided on the PTFE piston, the three factors work together to solve the problem of piston lubricant dependence and elastomer aging failure, and at the same time improve the repeatability of the titrator's test results from 0.09% to 0.04%.

[0026] 3. The bottom of the PTFE piston of this titrator is conical and fits into the cavity on the PTFE piston. When the solution in the burette is squeezed, it enters the cavity, thereby preventing air bubbles from adhering to the surface of the PTFE piston and solving the problem of air bubble retention on the piston. Attached Figure Description

[0027] Figure 1 This is a front view of the structure of this utility model;

[0028] Figure 2 This is a structural diagram of the piston rod of this utility model;

[0029] Figure 3 This is a structural diagram of the PTFE piston of this utility model;

[0030] Figure 4 This is a front sectional view of the structure of this utility model;

[0031] Figure 5 This is a side view sectional view of the piston rod structure of this utility model;

[0032] Figure 6 This is a cross-sectional view of the PTFE piston structure of this utility model;

[0033] Figure 7 This utility model Figure 3 Enlarged view of the structure at point A in the middle.

[0034] In the diagram: 1. Piston rod; 11. Mounting component; 12. Connecting component; 2. PTFE piston; 21. Connecting port; 22. Cavity. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, and not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0036] Please see Figures 1-7 This utility model provides an embodiment of a titrator piston, comprising: a piston rod 1, which is composed of a mounting part 11 and a connecting part 12, the outer surface of the connecting part 12 being threaded, and a PTFE piston 2 being disposed at the bottom of the outer surface of the piston rod 1; the PTFE piston 2 having a connection port 21 at the middle of its top, and a cavity 22 on the outer ring of its bottom; the piston rod 1 and the PTFE piston 2 being threadedly connected, thereby solving the problem of dynamic connection failure and preventing the piston from falling off during use; and the PTFE piston 2 having a cavity 22, which allows the PTFE piston 2 to be used with different burettes of the same model, and the presence of the cavity 22 makes it difficult for air bubbles to adhere to the surface of the PTFE piston 2.

[0037] In this embodiment, the outer surface of the mounting part 11 is provided with mounting holes. The mounting part 11 is connected to the limiting mechanism through the mounting holes to prevent the piston from moving out of the range and thus prevent the burette from being damaged.

[0038] In this embodiment, the PTFE piston 2 is composed of polytetrafluoroethylene (PTFE), which has excellent heat resistance, chemical resistance and electrical insulation properties, thus solving the problems of lubricant dependence and elastomer aging failure.

[0039] In this embodiment, the connection port 21 consists of a slot and a threaded hole. A retaining ring is provided at the bottom of the outer surface of the mounting part 11. The mounting part 11 is engaged with the PTFE piston 2 through the retaining ring and the slot. The connecting part 12 is threadedly connected to the PTFE piston 2 through the thread and the threaded hole. The mounting part 11 can be stably installed on the PTFE piston 2 through the cooperation between the retaining ring and the slot. At the same time, the connecting part 12 can be stably installed on the PTFE piston 2 through the cooperation between the thread and the threaded hole. The cooperation of the two improves the stability of the connection between the piston rod 1 and the PTFE piston 2 and solves the problem of dynamic connection failure.

[0040] In this embodiment, the outer surface of the PTFE piston 2 is provided with a multi-layer sealing structure, which consists of sealing rings, thus alleviating the problem of lubricant dependence.

[0041] In this embodiment, the bottom of the PTFE piston 2 is conical. Because the bottom of the PTFE piston 2 is conical, the solution in the burette is guided into the cavity 22 by compression, making it difficult for air bubbles to adhere to the surface of the PTFE piston 2.

[0042] Working principle: The user installs the piston on the transmission structure inside the titrator through the mounting part 11. Then, through the cooperation between the groove, the retaining ring, the thread and the threaded hole, the PTFE piston 2 can be stably and firmly installed on the piston rod 1. When the titrator is working, through the cooperation between the multi-layer sealing structure on the PTFE piston 2 and the cavity 22, the titrant solution in the burette will enter the cavity 22 when it is squeezed. At the same time, it can prevent the air bubbles generated when the titrant solution is squeezed from adhering to the surface of the PTFE piston 2.

[0043] For those skilled in the art, this invention is not limited to the details of the exemplary embodiments described above, and can be implemented in other specific forms without departing from the spirit or scope of this invention. Therefore, the embodiments of this invention are exemplary and not restrictive. The scope of this invention is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A titrator piston, characterized in that, include: The piston rod (1) is composed of a mounting part (11) and a connecting part (12). The outer surface of the connecting part (12) is provided with threads, and a PTFE piston (2) is provided at the bottom of the outer surface of the piston rod (1). The PTFE piston (2) has a connection port (21) at the top center. The connection port (21) consists of a groove and a threaded hole. The bottom of the outer surface of the mounting part (11) is provided with a retaining ring. The mounting part (11) is engaged with the PTFE piston (2) through the retaining ring and the groove. The connecting part (12) is threadedly connected to the PTFE piston (2) through the thread and the threaded hole. The outer ring at the bottom of the PTFE piston (2) is provided with a cavity (22).

2. A burette piston according to claim 1, characterised in that: The outer surface of the mounting component (11) is provided with mounting holes.

3. A burette piston according to claim 1, wherein: The PTFE piston (2) is composed of polytetrafluoroethylene (PTFE).

4. A burette piston according to claim 1, characterized in that: The outer surface of the PTFE piston (2) is provided with a multi-layer sealing structure.

5. A burette piston according to claim 1, characterized in that: The bottom of the PTFE piston (2) is conical.

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